Rebuilt transmission break-in???

tyhuck · June 28, 2012

Is there a break-in period with a rebuilt transmission. I know with engines there are some situations that you should avoid, and certain procedures that you whould perform to allow it to break-in properly. But, is there anything for a transmission? My builder said there is no break-in, but I want to make sure I dont tear it up by doing something I shouldnt do before the internal parts are conditioned properly.

Specifically, are there any towing or hard launch restrictions?

00Silverado4x4 · June 28, 2012

As long as your builder is offering a warranty, I'd go by what he says. That way if he's wrong and the trans goes out it'll be on his dime.

tyhuck · June 28, 2012

Good point, but its just the thought of it being more of an inconvenience than anything because they offer a 1 yr warranty.

gmtech4 · June 30, 2012

i rebuilt trannies for 3 yrs and i can tell you there is no break in ,,,,,,,,,

it is a hydraulic system that applys pistons to get a gear ratio ,thats it

new fiber and steel clutch discs need no break in ,they come together to lock a rotating hard part to achive a ratio/forward/reverse gear ...

here is how i road tested a rebuilt tranny ,,,,

fill it to cold full,,,

out the door and slowly start out in manual 1st ,shift up thru the gears slowly manually,,,

drive 6 miles or so at highway speed ,turn around ,,,

mash the throttle 100% thru the gears ,,,if something is gonna happen ,it will then lol,,,,

take it back in the shop ,pull the stick,it is always at full hot running of course for all level checks,,,,

peek underneath for any leaks ,,,never one lol

park it ,,,,finish work order and move on to the next blown up tranny !!!!!!

Doug_Scott · June 30, 2012

Rebuilt 904 and 727 trans at Chrysler dealership for years, no breakin required, assuming rebuild was done correctly. I would believe the rebuilder before believing someone on the internet though.

tyhuck · June 30, 2012

Got the truck back today and everything seems to be in great shape now. The guys at the shop had a pile of old worn out parts in a box for me when I got there to pick it up. Looks like my trans was in worse shape than I thought. I would assume that the previous owner never changed the fliud (87K miles) and when I added some fresh fluid to it, it started slowly letting go. Thats just my assumption since its only been about 4K since I changed it.

Anyway, so far Im pleased with it. ONly drove it a few miles, but I tested it out a little. They gave me the paperwork for the Transgo shift kit they installed, and it says that the shifts will firm up after a few miles. We'll see how she turns out after a few days.

ONe thing Im still unsure about though. I asked the builder how oftern to change the filter and fluid (just the 5qts in the pan) and he said dont worry about miles, just change it every year. For me thats no big deal (I only average 12k-15k per year) but what about these guys that run 100k+ in a year? What about my truck, if I suddenly have to start driving more and put more miles on in a year? How often should I change it then?

These are just things that pop into my head after hours, so I ask here because I may never remember during business hours.

elcamino · July 1, 2012

Just buy better ATF then the cheapest stuff most rebuilders use. To them ATF is ATF, so buy the cheapest and change it often, we need the business.

For the average person who does not tow, drive a lot of miles or othewise abuse the vehicle, you do not need to change the ATF every year IF YOU USE GOOD ATF and that not the stuff that comes from a drum with a name on it you never heard of.

tyhuck · July 1, 2012

He said they use Valavolene or Mobil Dex/Merc (cant remember exactly). I know it was a name brand but IM only 60% sure he said Valvolene, but that may be because its the brand I use.

I was planning on changing it around every 15K. Does this sound about right?

I kinda feel like my truck gave it up after adding the Dex VI (synthetic), but it was definately on its downhill trek anyway. Just to be safe, Ill probably keep running the Valvoline Dex/Merc, which is actually Dex III.

One more thing I though about after looking underneath and noticing fresh fluid on the transfer case drain plug. Do you have to dran the T-case to rebuild the transmission? I was planning on replacing the fluid anyway since it has probably never been changed either, but I wont worry about it if the transmission shop already did it. But, the fluid looked kinda gold (not really enough on my finger to really tell), and from what I have read, the fluid my autotrac needs is blue. Im gonna call tomorrow to make sure that they used the right fluid if they in fact did change it out. But, I want to know what kind of damage could happen if I drive the truck in 2wd with the wrong fluid in the t-case. I almost needed 4wd this weekend, but was scared to use it becausue of my uncertainty of the fluid in use.

Doug_Scott · July 1, 2012

From my experiences, changing trans fluid on a used vehicle that has never had it done, or on a vehicle that has black or burnt trans fluid is likely to experience a trans failure shortly after the change is done. New trans fluid is an excellent solvent for trans fluid varnish. That varnish will help seals keep their seal, but if it gets cleaned up by new fluid, the clutch packs will start to slip due to the seal not being able to hold the pressure.

The trans fluid standards have minimum requirements. If the fluid meets those standards, it is fine for use in your transmission. It is so good, that the vehicle manufacturer will warranty the trans for 5 years, 100,000 miles. If you can prove you followed the severe use maintenance schedule, vehicle manufacturer will repair the failed transmission if within the time/distance of the warranty. Note that virtually no one qualifies for the "normal use" schedule.

jdelrizzle · July 1, 2012

So that being said when do you recommend a tranny service?

KMGZ400 · July 3, 2012

From my experiences, changing trans fluid on a used vehicle that has never had it done, or on a vehicle that has black or burnt trans fluid is likely to experience a trans failure shortly after the change is done. New trans fluid is an excellent solvent for trans fluid varnish. That varnish will help seals keep their seal, but if it gets cleaned up by new fluid, the clutch packs will start to slip due to the seal not being able to hold the pressure.

The trans fluid standards have minimum requirements. If the fluid meets those standards, it is fine for use in your transmission. It is so good, that the vehicle manufacturer will warranty the trans for 5 years, 100,000 miles. If you can prove you followed the severe use maintenance schedule, vehicle manufacturer will repair the failed transmission if within the time/distance of the warranty. Note that virtually no one qualifies for the "normal use" schedule.

i agree. i would never touch the fluid on a trans with over 50k miles. i made the mistake of just doing a trans flush on my 2003 suburban with 111,000 miles, and the trans completley blew at 117,000 miles.

have 112,000 on my 2001, and 119,000 on my 2003. never touched the trans fluid and never will

gmtech4 · July 3, 2012

follow whats in the owners manual ,you're thinkin to much into this ,,there is no combustion contamination like engine oil thats why the change interval is high ,,,relax

i never changed t case oil when i did a build unless it looked like crap ,,never lost a drop takin tcase down,,lol or putting it back in !!!! save time= money in pocket !!

do you guys think changing the oil and filter blows up trannies ???? thats quite a statement with no proof,,,i dont buy it myself ,,,conspiracy theory at its worst i say

jaredlucky16 · July 3, 2012

Its easier to drop the t case out with it still attached to the trans then seperate them atleast on the new body style

jdelrizzle · July 3, 2012

I did a Trans flush on my 2004 impala, not knowing any better, then it had 80k and now it's pushing 200k, drove it from el paso to fort hood numerous times in the texas summer heat, not to mention the hills and curves in between, When I got it flushed the quick lube guy called me over to look at the burnt, black ATF. I guess I got lucky, I would never flush the tranny on my truck.

tyhuck · July 3, 2012

I didnt flush it, I just changed the filter and replaced the fluid that was lost from the pan. I guess doug_scott's post makes sense. Its probably one of those situations where it is good to change it regularly, but once its been neglected, you shouldnt mess with it for risk of braking something. Sounds a lot like those threads on Seafoam. Some people can use it with great success, but others end up cleaning out the carbon, which was the only thing keeping their engine from leaking like a seive.

On a slightly different, but related topic.

The builder claimed that the fluid will break down due to age. To use his words, "Its just like motor oil. You need to change it after it gets so old, regardless of mileage." I know oil change places put dates on their little reminder stickers, but does anyone really follow that? I dont, I just look at mileage.I just dont see how there is a difference between the oil sitting in my engine or transmission, or sitting in a bottle on a store shelf. Using that mentality, they should put an expiration date on bottles of oil.